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Mars rover Curiosity must rely on aging satellite to relay messages

August 5, 2012 | 1:20
pm

Scientists are attempting to deposit the largest and most advanced machine ever sent to another planet on Mars on Sunday night –- but they will know the spacecraft’s fate in “real time” only if they can get an aging satellite with a missing part to cooperate.

Curiosity, NASA’s roving geochemistry laboratory, is scheduled to land on the surface of Mars at 10:31 p.m. PDT. At the same moment, the Mars satellite known as Odyssey will pass overhead.

Because the Earth will have “set” below the Mars horizon prior to landing, the only way that messages from Curiosity indicating that it is safe can be relayed immediately to scientists on Earth is if Odyssey can act as a relay system.

Odyssey is more than 10 years old; it entered into orbit around Mars in the fall of 2001. What’s more, it is operating without a key part -– an angled wheel that allows scientists to precisely orient the satellite.

There are three of those wheels aboard Odyssey -– and about six weeks ago, one of them stopped working. There is a backup device known as a “skew wheel,” but it had not been turned on for 10 years, said Doug McCuistion, director of NASA’s Mars Exploration Program.

Odyssey will be flying close to the horizon during Curiosity’s landing, so in order to “see” what’s going on, the satellite will have to roll to one side about 15 minutes before Curiosity strikes the Martian atmosphere -- about 10 p.m. PDT.

Weeks ago, initial efforts to maneuver Odyssey using the backup wheel sent the satellite into "safe mode"; if that happens Sunday night, devices on the satellite needed to speak to scientists on Earth would likely be rendered inoperable.

That doesn’t mean Curiosity will fail -– but it does mean that scientists will endure a long night of waiting for other satellite passes before they can confirm that their $2.5-billion mission has succeeded.

Also Sunday, with Curiosity still on a near-perfect course for landing, scientists at the Jet Propulsion Laboratory in La Cañada Flintridge, which is managing the mission, said that they had passed up a final opportunity to correct the spacecraft’s trajectory.

Curiosity was “very healthy,” said mission manager Brian Portock.

“In cellphone speak, we have a full set of bars,” Portock said. “The flight team is feeling really good about the spacecraft.”

“Tonight’s it -- the Super Bowl of planetary exploration,” said Doug McCuistion, director of NASA’s Mars Exploration Program. “We score and we win -- or we don’t score and we don’t win.”

“If we succeed, it will be one of the greatest feats in planetary exploration -- ever,” McCuistion said. “The science at Mars is crucial to key questions in science: Are we alone?”

Scientists have one more chance this afternoon to give Curiosity a more precise understanding of where it is, but said the craft’s course was solid enough that they would likely pass up that opportunity as well.

“The team is ready. The spacecraft is ready. It’s to the fates,” said Adam Steltzner, a leader of the entry, descent and landing team. “We are rationally confident and emotionally terrified.”

Curiosity is the size of a small car, and is equipped with a suite of powerful instruments and capable of vaporizing rocks and ingesting Martian soil.

If it succeeds, the mission is expected to revolutionize scientists’ understanding of Mars by scouring an ancient meteor crater and a mountain for the building blocks of life in an effort to determine whether the planet is or was habitable.

The craft is also expected to pave the way for important next steps in deep-space exploration, including sample return and potential human exploration. President Obama has established a goal of sending astronauts to Mars in the 2030s.